Lithium periodates

Three periodates can be obtained by the action of lithium carbonate on periodic acid in aqueous solution. According to Rammelsberg, when sufficient carbonate to neutralize the acid is employed, crystals are deposited, probably the ortho-salt, Li5IO6; but with a smaller proportion of carbonate a salt, Li4I2O9,3H2O, is formed, which at 200° C. loses water, yielding a salt, probably Li2H3IO6. Addition of periodic acid to the aqueous solution of the complex tetra-lithium salt produces the meta-periodate, LiIO4.

In more recent work by Rosenheim and Loewenthal, it was not found possible to prepare Rammelsberg's ortho-salt or his meta-salt. One molecule of periodic acid reacts with two molecules of lithium hydroxide, precipitating colourless, microscopic spherules of the salt Li3H2IO6. On standing, the mother-liquor gradually deposits colourless, small, six-sided bipyramids of the formula Li2H3IO6.